Line failure notifying apparatus for terminal apparatus

Abstract

To prevent erroneous recognitions of line failures by a network apparatus, an alarm notifying controller region is provided independent from an actual data region in a connection between a line interface of the network apparatus and a terminal interface unit (line set). When a line is set within the network apparatus, an alarm notification path from the line interface to the line set is simultaneously set. When a line failure is detected by the line interface, information is notified the alarm notification path to all of the line sets connected to this line interface. In the line sets, a signal state of an interface is changed with respect to each sort of terminal interfaces, so that the line failure is notified to the terminal.

What is claimed is:  
     
       1. A network apparatus comprising: 
       means for receiving a bit stream from each of terminal side apparatuses, each bit stream is replaced to a fixed value when a failure of a line between network apparatuses is detected;  
       means for multiplexing the plurality of bit streams from the terminal side apparatuses in series to generate a multiplexed bit stream; and  
       means for transmitting the multiplexed bit stream to the other network apparatus via a control line, the other network apparatus is connected to the network apparatus via the line and monitoring the failure of the line.  
     
     
       2. A network apparatus to which a plurality of terminal apparatuses are connected, comprising: 
       a plurality of terminal interfaces for receiving signals via lines connected from the plural terminal apparatuses;  
       multiplexing means for bit-multiplexing signals derived from the plural terminal interfaces thereby producing a multiplexed bit stream signal;  
       failure-occurrence-notifying bit producing means for replacing said multiplexed bit stream signal by a failure-occurrence-notifying bit stream which implies an occurrence of a failure when a failure occurrence in a line is detected, wherein part of said multiplexed bit stream signal are reversed in a fixed value data stream; and  
       failure-problem processing means for detecting said failure-occurrence-notifying bit stream within said network apparatus to thereby process a line failure problem with respect to a terminal apparatus.  
     
     
       3. A network apparatus as claimed in  claim 2 , further comprising: 
       bit operating means interposed between said multiplexing means and said failure-occurrence-notifying bit producing means, for rewriting said bit stream signal, thereby to prevent generating a certain bit stream which implies an occurrence of a failure.  
     
     
       4. A network apparatus to which a plurality of terminal apparatuses are connected, comprising: 
       a terminal interface for receiving signals via lines connected from the plural terminal apparatuses, including failure notifying means for notifying an occurrence of a failure to said terminal apparatuses;  
       a line interface connected to an external line, including failure detecting means for detecting a failure of said external line;  
       an actual data path for connecting said terminal interface to said line interface within said network apparatus, and transmitting actual data from said line interface to said terminal interface; and  
       a failure notification path set to said failure detecting means and said failure notifying means.  
     
     
       5. A network apparatus as claimed in  claim 4  wherein: 
       said network apparatus is further comprised of:  
       a plurality of terminal interfaces each connected via an external line of said network apparatus to a plurality of other network apparatuses and other terminal apparatuses, and also connected to said plurality of terminal apparatuses;  
       said line interface includes:  
       line condition monitoring means for monitoring the occurrence of the failure with respect to each of the external lines; and  
       a failure notifying unit for notifying the occurrence of said failure to a terminal apparatus of said plurality of terminal apparatus communicated with the external line where the occurrence of the failure is detected by said line condition monitoring means; and  
       failure notification paths are set between said failure notifying unit and each of said plurality of terminal interfaces.  
     
     
       6. An ATM switching apparatus interposed between a plurality of own terminal apparatuses and an external line, comprising: 
       a terminal interface for receiving signals via lines connected from said plurality of own terminal apparatuses;  
       an ATM switch for switching a cell between said plurality of own terminal apparatuses and said external line;  
       a line interface for receiving signals via the external line and for including failure detecting means for detecting a failure occurred in the external line;  
       path monitoring means for specifying a path of the external line where the failure happens to occur;  
       failure-notifying cell producing means for producing and transmitting a failure-notifying cell for notifying an occurrence of a failure by changing a state of a payload signal to such a terminal apparatus for connecting with the external line where the failure happens to occur in response to information transmitted from said failure detecting means, or said path monitoring means; and  
       output control means for instructing said ATM switch to be turned OFF.